1. Field of the Invention
The present invention relates to a display device having a plurality of display portions.
2. Description of the Related Art
A liquid crystal display device is widely used as a display device for various kinds of electronic devices such as a cellular phone, a computer, a personal digital assistant, and a video game. Liquid crystal display devices include reflective ones, transmissive ones, and transflective ones. As a display device for a portable electronic device such as a cellular phone described in the above, a transmissive liquid crystal display device and a transflective liquid crystal display device are widely used. Because a liquid crystal display panel is a non self light emitting type display element, an illuminating device (backlight) is necessary for a transmissive or transflective liquid crystal display device.
Cellular phones include so-called folder type (flip type) ones. FIG. 5 schematically illustrates a folder type cellular phone. FIG. 5A illustrates the cellular phone in an opened state while FIG. 5B illustrates the cellular phone in a folded state. As illustrated in FIGS. 5A and 5B, in this type of a cellular phone, a main body portion 01 having a plurality of buttons disposed thereon and a display portion 02 are connected by a hinge 03 so that the display portion 02 is opened and closed with respect to the main body portion 01. The display portion 02 has a main liquid crystal display panel 04 disposed on an inner side when folded and an auxiliary liquid crystal display panel 05 disposed on an outer side when folded. Specifically, in the display portion 02, the main liquid crystal display panel 04 and the auxiliary liquid crystal display panel 05 are disposed back to back. In order to illuminate the main liquid crystal display panel 04 and the auxiliary liquid crystal display panel 05 from respective sides of the back surfaces thereof, a main illuminating device and an auxiliary illuminating device are provided in some cases.
When the main and auxiliary liquid crystal display panels are thus illuminated by separate illuminating devices, because two illuminating devices are necessary, costs and the number of parts are increased, which raises problems of increased weight and increased size. Therefore, products in which the main and auxiliary liquid crystal display panels are illuminated by one illuminating device for reduction in thickness are widely provided. In such a product, a light guide plate is disposed between the main liquid crystal display panel and the auxiliary liquid crystal display panel. A light emitting diode emits light to a side surface of the light guide plate. The incident light is emitted from a light emitting surface on an upper surface side of the light guide plate (surface on the side of the main liquid crystal display panel) and from a light emitting surface on a lower surface side of the light guide plate (surface on the side of the auxiliary liquid crystal display panel) to illuminate the main and auxiliary liquid crystal display panels. In this case, in order to make larger an amount of light illuminating the large main liquid crystal display panel than an amount of light illuminating the small auxiliary liquid crystal display panel, a transflective sheet which partly transmits light and partly reflects light is disposed between the light guide plate and the auxiliary liquid crystal display panel in some cases (see, for example, JP 2004-87409 A).
In the structure in which the main and auxiliary liquid crystal display panels are illuminated by using one illuminating device, because light is emitted from both surfaces of one light guide plate, the color of the backlight of the main liquid crystal display panel and the color of the backlight of the auxiliary liquid crystal display panel are the same. Normally, the color of the backlight (that is, the color of light emitted from the illuminating device) is white. This is because a color liquid crystal display panel can perform optimum color display by being illuminated by white backlight.
However, while a color liquid crystal display panel is used as the main liquid crystal display panel, a monochrome liquid crystal display panel is used as the auxiliary liquid crystal display panel in some cases. In such a case, the auxiliary liquid crystal display panel can naturally perform only monochrome display and can not perform chromatic display. If, although various colors are applied to the main body portion and a case of the display portion of a cellular phone, the auxiliary liquid crystal display panel only performs monochrome display and can not perform chromatic display, such a cellular phone is less attractive as a product. In order to enhance the appearance of the cellular phone as a product (from the viewpoint of design), it is effective that the monochrome liquid crystal display panel is chromatically colored even if only in one color.